1. Field of the Invention
The invention concerns a safety device for controllable high-power semiconductor components to protect them against too high rates of voltage increase dU/dt, and a method of producing such a safety device.
2. Description of the Prior Art
When thyristors are incorporated in electrical circuits they are either provided with a normal load far under the permissible limit or must be protected by a special circuit. This is particularly important in high-voltage rectifiers in which multiple series connections of thyristors are used, because in such installations there is very great danger of an unequal and excessive loading of individual thyristors.
The voltage applied to the thyristor is limited by RC-elements (cf. e.g. H. Laber: "High-voltage rectifiers with thyristors", Siemens Zeitschrift 47 (1973), p. 823 ff.) and/or by semiconductor voltage limiters (cf. e.g. Brown Boveri Mitteilungen 1972, p. 476 ff.).
H. Laber's article also tells how to protect against too rapid voltage rises dU/dt that also can cause unwanted firing of the thyristors, by suitable choice of capacitances or inductances.